Lifting-jack



L. 1. HALL.

LIFTING JACK. APPLICATIONAFILEU DEC.29, I9I6.

Patented May 11, 1920.

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LOUIS U. HALL, OF FREEPORT, NEW YORK, ASSIGNOR T0 COLUMBIAN BRONZE CORPORATION, OF FREEPORT, LONG- ISLAND, NEW YORK, A CORPORATION OF NEW YORK.

LIFTING-JACK.

Specification of Letters Patent. P te t d May 11, 1920.

Application filed December 29, 1916. Serial No. 139,440.

To all whom it may concern Be it known that l, LOUIS J. HALL, acitizen of the United States, and resident of Freeport, county of Nassau, and State of New York, have invented certain new and useful Improvements in Lifting-Jacks, of whi h the following is a specification.-

This invention relates to lifting jacks, and more particularly to that type of jack in which a vertical lifting rod raised and lowered step-by-step by means of a lover.

The object of the invention is the provision of a jack of the type set forth, so constructed that the lifting bar will automatlcally drop to its lowermost position when lowered sufiiciently to relieve the bar from the weight of the load. I

In the drawings, Figure 1 is a side elevation, partly in section, the parts being shown in position to raise the lifting bar;

Fig. 2 a detail side elevation partly in section, showing the parts in lowering position;

Fig. 3 a view similar to Fig.2, showmg the lifting bar in its lowered position after being relieved of the load; and Fig. 1 a transverse section through the hancle and lever socket.

Referring to the various parts by numerals. 1 designates the frame or standard of the jack, and 2 designates the lifting bar having a load-supporting head 3 rotatably mounted on the upper end thereof. The lifting bar 2 is slidably and rotatably mounted in bearings 1 and 5 in the frame 1, and is formed intermediate its ends with a series of frusto-conical teeth 6. Rigidly secured alo one side of the lifting bar is a bar I.

p A sprlng 8, secured to the frame at one end,

'slidably engages and presses against one side of the 7 and tends to rotate the lifting bar 2. A. holding detent 9, pivotally mounted in the frame, is normally held with its free end engaging the teeth on the lifting bar by means of a coil spring 10. The detent 9 is formed with a laterally and forwardly extending shoulder 11 which is adapted to be engaged by the side of bar 7 opposite the side thereof engaged by spring 8.

An operating lever 12 is pivoted intermediate its ends on a horizontal pivot 13 in the frame. A pawl let is pivotally mounted intermediate its ends on the inner end of lever 12, on a horizontal pivot pin.

The upper end of pawl 14 is normally-held in engagement with the teeth 6 on the lifting bar 2, by means ofa coil spring 15, connected with the lower off-set end 141 of said pawl and with the lever 12.

The outer :end of the operating lever 1 is. formed with a socket 16 1 in which is mounted a rotatablesleevel? ihavinga lug 18 projecting through a slot19 inthesocket. An operating handle 20 is slidably held in the sleeve 17 so as to be readily detachable therefrom. The handle is formed with a longitudinal rib or key 21 adapted to en age a correspondinggroove in the sleeve 1 to connect said sleeve with the handle to .r0 tate therewith.

A pawl-releasing bar 22 is slidably mounted along one side of the lever 12 torock therewith, and is guided by the pivot pin 13 0f the lever. The releasing'bar 22 is slotted as shown at 23, to permit longitudinal movementof said bar. .At itsouter end the bar 22 is provided with a cam slot .24 through which the outer .end of lug 18 on sleeve l'l' projects. The bar 22 is heldin its adjusted position by the lug 18. The inner end of the releasing bar 22 .is bent inwardly toward the lifting bar2 to form a lug 25 adapted to engage the side of the bar 7 opposite the side engaged by spring 8, to limit the extent of rotation of the lifting 1 bar 2 .by said spring.

With the parts in the position shownin Figs. 1 and 2, to lift the load, the handle 20 of leverv 12 is raised. andlowered to raise and lower lifting pawl 14. It will be obvious that the pawl 14; will raisethe bar when the handle 20 is lowered, and will ride over teeth 6 when the handle is raised,,while'. holding-detent 9 will 'rideover teeth fiduring the upward movement of the bar '2 and engage under one ofsaid teeth to hold the bar in raised position when the upward movement of the bar ceases.

To lower the bar with the loadsupported thereby, the handle 20 is given a partial r0.- tation torotatefsleeve 17 in socket 16 and cause the lug 18 carried by the sleeve to move in slots 19 and 2 1 and thus move the releasingbar or slide 22 inwardly to the position shown in. Figs. 3 and 4. This movement carries lug 25 on the releasing bar or slide 22 away from bar 7. The lifting bar .2 .is preventedfrom rotating in its bearings 4 and under the influence of spring 8, by the weight of the load supported thereby.

To lower the load the handle is raised to move the innerends of the leverand releas- 7 a pivoted stop 27 The stop 27 is pivotally connected with the slidable releasing bar 22,

at 28, and is normally held in the position shown, by a stop pin 29 on bar 22. When the handle is rotated and the bar 22 carrying the lug is moved inwardly, as hereinbefore described, the free end of stop 27 rides over a lug projecting from the frame, and is held in the path of the offset end 14 of pawl 14: by said lug. When pawl 14; engages stop 27 the pawl is rocked on its pivot to disengage its upper end from tooth 6 and permit the pawl to pass over the previously engaged tooth on the downward movement of handle 20, and engage the tooth next above. As pawl 14 moves into engagement with said. tooth the lug 25 on releasing bar 22 engages under shoulder 11 on detent 9 and temporarily holds said detent out of engagement with the teeth on the lifting bar 2, so as to permit the bar to lower on the next upward movement of handle 20, with the bar and load supported by pawl 14. As the bar moves downwardly lug 25 is carried downwardly and detent 9 thereupon snaps under the next tooth on the lifting bar and supports the load when pawl 1 1 is released and moved upwardly as heretofore described. The load is thus lowered step-by-step until the bar 2 is relieved of the weight of the load. As soon as the bar 2 is relieved of the load the pressure of spring 8 partially rotates the bar in its bearings l and 5 and the detent 9 is moved out of engagement with the teeth 6 by pressure of the bar 7 against the shoulder 11 of said detent 9. l/Vhen pawl 14: is released from the teeth 6 by stop 27 on its next downward movement, the bar 2 is unsupported and drops to its lowermost position in the frame.

The lug 25 on releasing bar 22 serves to limit the extent of the rotary movement of bar 2 under the influence of spring 8, and restores the bar 2 to the position shown in Fig. 1 when the handle is rotated to restore the releasing bar 22 to the position shown in Fig.1. There will be a slight oscillation of the lifting bar 2 and bar 7, due to the movement of lug 25 in an arc while the bar 2 is being raised to engage the load, but this movement is insuflicient to disengage detent 9 from the teeth, and the final upward movement of pawl 14D and lug 25 as pawl 14 carries the bar upwardly into engagement with the load, carries the bar 7 to the position shown in Fig. 1, where it is held by the weight of the load on the bar 2.

The parts are so proportioned that the lug 25 on bar 22 will not engage shoulder 11 on detent 9 when the bar 22 is in the position shown in Fig.1. When, however, said bar is moved inwardly to releasing position by rotating the handle 20, the increased throw of the inner end of the bar causes lug 25 to engage under the shoulder 11 and release the detent 9, as hereinbefore described.

What I claim is:

1. In a jack, the.combination of a frame, a toothed lifting bar slidably mounted thereon, an operating lever having a rotatable hand gripping portion, a lifting-bar shifting pawl carried by said lever and adapted to normally engage the teeth on said bar, a holding detent normally engaging in the teeth on said bar, means movable by rotating the hand-gripping portion of the lever into and out of coiiperative relation with the pawl and detent for alternately disengaging said pawl and detent when the operating lever is vibrated to lower said lifting bar, and means whereby said bar is released from the pawl and detent when relieved of the load.

2. In a ack, the combination of frame, a toothed lifting bar slidably mounted therein, an operating lever, a lifting-bar shifting pawl carried by said lever adapted to normally engage the teeth on said bar, holding detent normally engaging said teeth, means shiftable into and out of cooperative relation with said pawl and detent adapted when in cooperative relation therewith to alternately disengage said pawl and detent when the operating lever is vibrated, and means for automatically releasing said detent and holding it out of engagement with the bar when said bar is relieved of the load, whereby said bar may drop to its lowermost position upon the next movement of the operating lever to release said pawl.

3. In a jack, the combination of a frame, a toothed lifting bar slidably mounted therein, an operating lever, a pawl carried by said lever adapted to normally engage the teeth on said bar, a holding detent normally engaging said teeth, means carried by said lever and manually movable relatively thereto'adapted when in one position on said lever to alternately disengage said pawl and detent when the lever is vibrated to lower said bar, and means ered sufliciently to be relieved of the load for shifting and holding said detent out of engagement with the teeth on the bar to thereby permit the bar to drop to its lowermost position when the pawl is next disengaged.

4. In a jack, the combination of a frame, a toothed lifting bar slidably mounted therein, an operating lever having a rotatable hand-gripping portion,a pawl carried by said lever adapted to normally engage operable automatically when the bar is low 1 "ass sses tent disengaging means for shifting said means relatively to the lever when said gripping portion-is rotated, and automatically actuated means for holdin said detent out of engagement with the bar when said bar is relieved of the load.

5. In a jack, the combination of a frame, a toothed lifting bar slidably mounted thereon, an operating lever, a pawl carried by said lever adapted to normally engage the teeth on said bar, a holding detent normally engaging said teeth, a releasing bar slidably mounted on said lever to move longitudinally thereof and to 'Wibrate therewith, means carried by said releasing bar 'ada )ted to alternately disen 'a ge said )awl and detent when the lever is vibrated to lower the lifting bar, and automatically actuated means for disengaging said detent and holding it out of the path of said teeth when the lifting bar is relieved of the weight of the load, whereby the bar may drop by gravity to its lowermost position when the pawl is released by the operating lever.

.6. In a jack, the combination of a frame, a toothed lifting bar slidably mounted therein, an operating lever, a pawl carried by said lever adapted to normally engage the teeth on said bar, a holding detent normally engaging said teeth, a releasing bar slidably mounted on said lever, connections between said releasing bar and lever for shifting said bar longitudinally of the lever, means carried by said releasing bar adapted when said bar has been shifted inwardly to alternately disengage said pawl and detent when the lever is vibrated, and automatic means operable when the releasing bar is in lowering position for disengaging said detent and holding it out of the path of said teeth when the lifting bar is relieved of the load.

7. In a jack, the combination of a frame, a toothed lifting bar slidably and rotatably mounted therein, an operating lever, a pawl carried by said lever adapted to normally engage the teeth on said lifting bar, a hold ing detent normally engaging said teeth, a releasing bar slidably mounted on said lever, means carried by said releasing bar adapted to alternately disengage said pawl and detent when said bar has been moved to releasing position to lower the lifting bar, and means for rotating said lifting bar when said bar is relieved of the load to disengage said detent and hold the same out of the path of the teeth on the lifting bar to permit the bar to drop to its lowermost position when said pawl is disengaged.

8. In a jack, the combination of a frame, a toothed lifting bar slidably and rotatably mounted therein, an operating lever, a rotatable handle connected with said lever, a

pawl carried by the lever adapted to normally engage the teeth on the lifting bar, a holding detent normally engaging said teeth, a releasing bar slidably mounted on said lever, means carried by said releasing bar adapted to alternately disengage said pawl and detent when the releasing bar is shifted to releasing position, connections between said handle and releasing bar for shifting the bar to and from releasing position, and means for automatically rotating said lifting bar when said bar has been lowered sufficiently to relieve the same of the load to disengage said detent and hold the same out of the path of the teeth on the lifting bar, whereby said bar will drop to its lowermost position when the pawl is released by a subsequent vibration of the operating lever.

9. In a jack, the combination of a frame, a toothed lifting bar slidably and rotatably mounted therein, an operating lever, a rotatable handle connected with said lever, a pawl carried by the lever adapted to normally engage the teeth on the lifting bar, a holding'detent normally engaging said teeth, a releasing bar slidably mounted on said lever, means carried by said releasing bar adapted to alternately disengage said pawl and detent when the releasing bar is shifted to releasing position, connections between said handle and releasing bar for shifting the bar to and from releasing position, means for automatically rotating said lifting bar when the same has been lowered sufficiently to be relieved of the load, and means carried by said lifting bar adapted when the bar is rotated to disengage said detent and hold it out of engagement with the teeth.

10. In a jack, the combination of a frame, a toothed lifting bar slidably and rotatably mounted therein, an operating lever, a rotatable handle connected with said lever, a pawl carried by the lever adapted to normally engage the teeth on the lifting bar, a holding detent normally engaging said teeth, a releasing bar slidably mounted on said lever, means carried by said releasing bar adapted to alternately disengage said pawl and detent when the releasing bar is shifted to releasing position, connections between said handle and releasing bar for shifting the bar to and from releasing position, means carried by said lifting bar adapted to disengage said detent when the bar is rotated and hold the same out of the path of the teeth on the bar, means for automatically rotating the lifting bar when the bar has been relieved of the load, and means carried by the releasing bar adapted to restore the lifting bar and detent-releasing means to normal lifting position when said releasing bar is moved out of releasing position.

11. In a jack, the combination of a frame, a toothed lifting bar slidably and rotatably mounted therein, an operating lever, a rotatable handle connected with said lever, a pawl carried by the lever adapted to normally engage the teeth on the lifting bar, a holding detent normally engaging said teeth, a releasing bar slidably mounted on said lever, means carried by said releasing bar adapted to alternately disengage said pawl and detent when the releasing bar is shifted to releasing position, connections between said handle and releasing bar for shifting the bar to and from releasing position, means carried by said lifting bar adapted to disengage said detent when the bar is rotated and hold the same out of the path of the teeth on said bar, a spring engaging said detent-releasing means and adapted to rotate the lifting bar when said bar is lowered sufficiently to be relieved of the load, and means carried by the releasing bar adapted to restore the lifting bar and detent-releasing means to normal lifting position when the releasing bar is moved out of releasing position.

12. In a jack, the combination of a frame, a lifting bar slidably and rotatably mounted in said frame, means for raising the lifting bar step by step, means for lowering said bar step by step, and means for automatically rotating said lifting bar when it is lowered to a point where it is freed from its load, thereby permitting it to drop to its lowermost position.

13. In a jack, the combination of a frame, a vertically movable lifting bar rotatably mounted in said frame, means for raising and lowering said bar step by step, and means for rotating said lifting bar whereby said bar may be released from the raising and lowering means and permitted to drop to its lowermost position.

14. In a jack, the combination of a frame, a lifting bar rotatably mounted in said frame, means for raising the lifting bar step by step, means for lowering said bar step by step, and means automatically operating during the lowering of said lifting bar for rotating said bar to release the bar from the lowering means, thereby permitting it to drop to its lowermost position.

15. In a jack, the combination of a standard, a lifting bar, an operating lever, pawl and detent mechanism operable by said lever for raising and lowering the lifting bar step by step, and load-controlled means operating automatically when the bar is lowered sufiiciently to be relieved of the load to shift and hold said detent out of engagement with the bar during a subsequent movement of the lever to disengage the pawl from the bar.

16. In a jack, the combination of a standard, a reciprocable and rotatable lifting bar, an operating lever, means operable by said lever for raising and lowering the bar step by step, spring means operating automatically to rotate the bar when the bar is re lieved of its load, and means rotatable with the bar for adjusting said lever-operated means to free the bar upon actuation of the lever after the bar is relieved of its load.

In testimony whereof I hereunto afiix my signature.

LOUIS J. HALL. 

